Health Studies

Evidence is mounting that the healthiest diets are built around a variety of minimally processed, whole foods, and can’t be reduced to specific nutrients. To determine saturated fat’s role in heart disease risk, researchers from California reviewed the existing literature about saturated fats, polyunsaturated fats, carbohydrates, and heart disease. The scientists found that when saturated fat (found mostly in red meat and milk fat) is replaced with polyunsaturated fat (found mostly in nuts, seeds, and fish), heart disease risk decreases. However, when saturated fat is replaced with sugary refined carbohydrates, heart disease risk remains the same, if not worsens. The researchers also note a small, yet growing body of research that dairy fat (especially in fermented dairy, like yogurt), may be neutral (or even decrease risk) for heart disease. The researchers concluded that “overall dietary patterns emphasizing vegetables, fish, nuts, and whole versus processed grains form the basis of heart-healthy eating, and should supersede a focus on macronutrient composition.”Annual Review of Nutrition. 2015 July 17;35:517-43. (Siri-Tarino PW et al.) [Epub]

Med Diet Cuts Risk of Womb Cancer by Half

Endometrial cancer, also known as womb cancer, is largely determined by hormone levels in the body. However, new research shows that diet can play an important role in prevention. Combining the results of three large studies, Italian researchers analyzed the eating patterns of over 5,000 women in Europe (1411 with endometrial cancer, and 3668 controls) for their adherence to the Mediterranean diet. Those most closely following the Mediterranean diet were over 50% less likely to develop endometrial cancer than those with the lowest adherence to the Mediterranean diet. Additionally, researchers found that “the Mediterranean diet as a whole is a stronger determinant of endometrial cancer risk than the single dietary components,” emphasizing the importance of overall diet.British Journal of Cancer. 2015 May 26;112(11):1816-21. (Filomeno et al.)

Mediterranean Diet Can Improve Cognitive Function

The Mediterranean diet has long been studied for its role in heart health and aging, but emerging research suggests that it may also be protective for brain health. In a follow up to the PREDIMED study (where Spanish adults at risk for heart disease were randomly assigned to either a Mediterranean diet with four tablespoons of olive oil daily, a Mediterranean diet with one ounce of nuts daily, or a low fat controlled diet) researchers analyzed the relationship between diet and cognitive function. Of the 334 participants in this study with data on cognitive function, the scientists found that overall brain function significantly improved for both Mediterranean groups over the 4-year experiment, compared with the control group. Specifically, the nuts group significantly improved on tests of memory, while the olive oil group significantly improved on tests of reasoning, planning, and problem solving. This adds to the growing body of research that the Mediterranean diet is an important factor in healthy aging.JAMA Internal Medicine. 2015 May 11. [Epub ahead of print] (Valls-Pedret C et al.)

Traditional African Diet May Reduce Colon Cancer Risk

Colon cancer, the second leading cause of cancer death in the US, affects a greater proportion of African Americans than rural Africans, indicating that diet plays an important role in disease prevention. To see how traditional diets affect risk factors for colon cancer, researchers assigned 20 middle aged African Americans to a traditional, African heritage diet (averaging 55g fiber daily and 16% calories from fat, with foods like mangos, bean soup, and fish) and 20 middle aged rural South Africans to a typical American diet (averaging 12g fiber daily and 52% calories from fat, with foods like pancakes, burgers, fries, and meatloaf). In just 2 short weeks, the African Americans reduced the inflammation of their colons, improved their markers for cancer (including increased levels of butyrate, an anti-cancer chemical), and increased the diversity of their healthy gut bacteria. On the other hand, the rural Africans eating an American diet fared worse, producing more bile acid (a risk factor for colon cancer), while decreasing the diversity of healthy gut bacteria. These results indicate that an African heritage diet can help promote a healthy digestive tract (potentially reducing colon cancer risk), and that rapid improvements can come with a change to healthier foods.Nature Communications. 2015 Apr 28;6:6342. (O’Keefe SJ et al.)

Leafy Greens Can Keep Your Brain Young

It is no secret that green vegetables are some of the healthiest foods for our bodies, but new research shows that they are also good for our brains. Researchers in Chicago and Boston analyzed the eating patterns and cognitive abilities of over 950 older adults for an average of five years. The scientists found a significant decrease in the rate of cognitive decline for people who ate more green leafy vegetables (like spinach, kale, collards, and mustard greens). In fact, people who ate just one to two servings of leafy greens per day had the cognitive ability of a person 11 years younger than those who ate none.

Med Diet Cuts Heart Disease Risk by Nearly Half

Researchers have given us yet another reason to fill our plates with fruits, vegetables, whole grains, legumes, olive oil, and nuts! A European study followed more than 2,500 Greek adults for over a decade, tracking their medical records, lifestyle habits, and eating patterns. Those who most closely followed the Mediterranean Diet were 47% less likely to get heart disease, regardless of their smoking habits, age, family history, or other lifestyle factors. The scientists estimate that every one-point increase on the Mediterranean Diet score (a measure of how closely participants followed the Mediterranean Diet, on a scale of 1 to 55) is associated with a 3 percent drop in heart disease risk, so every little bit counts. In fact, the researchers found that the Mediterranean Diet was even more protective against heart disease than physical activity!Presentation at the American College of Cardiology’s 64th Annual Scientific Session. San Diego CA. March 15, 2015.

Doctors May Not Be Equipped for Diet Counseling

One of the great ironies of the healthcare system is that doctors are often untrained in the most basic of wellness practices: nutrition. In a survey of 236 physicians at a large US medical center (including cardiologists and internal medicine doctors and trainees), fewer than 14% felt adequately trained to discuss nutrition with their patients. Nearly all doctors (90%) recognized the Mediterranean Diet as protective against heart disease, but fewer than half (46%) realized that low-fat diets have not been proven to reduce heart disease risk. Additionally, many doctors had trouble identifying foods high in various nutrients, such as which fish are high in omega-3 fatty acids. These data highlight the importance of making reliable nutrition resources (specifically those relating to well researched eating patterns, such as the Mediterranean diet) available to the medical community. (Note: If you’re a healthcare professional who would like to learn more about the Mediterranean Diet, see here.)Presentation at the American College of Cardiology’s 64th Annual Scientific Session. San Diego CA. March 15, 2015.

Plant-Based Diets May Reduce Colorectal Cancer Risk

Colorectal cancer is the leading cause of cancer mortality, so learning more about dietary prevention is an important area of research. Scientists at Loma Linda University in California analyzed food patterns and health data from over 77,000 adults for an average of 7 years. After controlling for demographic and lifestyle factors (including age, smoking, physical activity, and family history), the researchers found that those who ate vegetarian diets had an approximately 20% lower risk of colorectal cancer compared with nonvegetarians. Researchers also found that pesco-vegetarians in particular (vegetarians who eat fish) had a much lower risk of colorectal cancer. These results support other studies linking the Mediterranean diet (a plant-based diet that features fish) with a decreased risk for colorectal cancer.JAMA Internal Medicine. 2015 March 9. [Epub ahead of print] (Orlich MJ et al.)

Peanuts Linked to Lower Mortality Across Different Ethnicities

Nuts and peanuts (technically legumes) are largely recognized as health promoting foods, but experts wondered if these benefits extend across all ethnic groups and income levels. In this study, researchers at Vanderbilt University analyzed nut intake in over 200,000 people, including a large group of Asian men and women in China, and a large group of low-income black and white men and women in the southeastern United States. For those with the highest nut consumption (mostly peanuts), mortality from all causes significantly decreased 17-21%, depending on ethnicity. Death from heart disease specifically (including ischemic heart disease) also significantly decreased across all ethnic groups for those eating the most nuts. The researchers identified this study as “strong evidence that the association of nut/peanut consumption with mortality does not vary by ethnicity “ or income level. Additionally, they conclude that “consumption of nuts, particularly peanuts given their general affordability, may be considered a cost-effective measure to improve cardiovascular health.”JAMA Internal Medicine. 2015 Mar 2. [Epub ahead of print] (Luu HN et al.)

Cardioprotective Effect of Mediterranean Diet

Ventricular hypertrophy, or the thickening and enlargement of heart ventricles due to the accumulation of scar tissue, is thought to be a root cause of many heart ailments. To investigate how diet relates to this condition, researchers analyzed eating patterns and left ventricular mass (the size of the left ventricle of the heart, where enlargement is most common) of over 1,700 adults without history of heart attack or stroke. The scientists found that those most closely adhering to a Mediterranean Diet had a left ventricular mass that was 4% less than the rest of the study population, a reduction greater than that observed in people with moderate-to-heavy physical activity (another factor that supports heart health). In fact, for each point increase on the Mediterranean Diet Score (0-9), left ventricular mass was 1.98g lower (average left ventricular mass was 189g).American Journal of Cardiology. 2015 Feb 15;115(4):510-4. (Gardener H et al.)